1. Field of the Invention
This invention pertains to static molds generally, and more particularly to molds used in the simultaneous formation of footings and walls of a monolithic cast static structure such as a commercial building or a home. The structure will most preferably be molded from concrete, though other materials could also find application.
2. Description of the Related Art
The building trade has been a part of history through all time. A seemingly infinite number of structures have been designed, frequently capitalizing on materials plentiful to a particular area or region. Dwellings have been constructed structurally from such plant based materials as straw, bamboo and wood, and have evolved to include "two by" natural lumber and engineered material construction. Various adobe, rock and earthen materials are also used, and brick and concrete are fabricated for the building trade from raw materials taken from the earth with minimal processing. Ice and snow have been used in the construction of igloos, and, in fact, even various natural formations such as caves have been converted to dwellings.
Buildings provide shelter for inhabitants and their possessions against the elements of nature. As recorded cumulative knowledge has expanded through time and experiences, mankind has learned to identify desirable features of a dwelling, including such things as resistance to storm and flood waters, extreme winds and temperatures, and even insects, rodents and other uninvited creatures of nature. In many regions and localities around the world, the wisdom and experience gained through time has been codified into various building regulations to help ensure safety and protection of a region's citizens and inhabitants. Whether legislatively mandated or not, it is most preferred that dwellings offer resistance to the environment, even in the case of an infrequent event such as severe weather, fire, flooding or other natural disaster. In addition, it is desirable that the building structure offer durability through as much time as possible, by resisting aging brought on by time and the elements. Low cost and simple construction are also desired, but may not always be associated with a particular material or structure.
One material which is associated with many desirable features is concrete, particularly when the concrete is further reinforced with steel. Steel reinforced concrete structures tend to be incredibly resistant to the elements, surviving incredible winds, floods, fires, ground contact, insects and extreme temperatures. As a result, concrete will last for many years and will survive most of the disasters that all too often destroy other buildings. In a reasonably designed and suited location, the life expectancy of concrete is measured in centuries rather than years. In fact, concrete in many applications may only be outlasted by relatively massive stone construction, which is far more expensive, much less available and far harder to convert into a building than concrete. Furthermore, and in part due to its massiveness, concrete offers other advantages such as thermal and physical mass which aid in wind and storm resistance and also provide a moderation of external temperatures.
In the residential construction industry, concrete is the material of choice for most footings and foundations, and many basement walls. In these below grade projects, standard timbers will not withstand ground contact. Furthermore, the surrounding soil will most often also be quite massive, and the structure needed to withstand ground forces and hydraulic pressures will desirably be quite rugged.
Nevertheless, concrete has been slow to gain widespread use in the above-ground home construction industry, even though frequently used for foundations and basements. In no significant part this has been due to the cost of constructing an above-ground structure from concrete. Heretofore, in order to cast the concrete into the shape of a building or dwelling, the concrete had to be retained in some type of a static mold. These molds have, in the past, been manufactured from wood at the job site, or, in some cases, from steel or aluminum for more long term use by concrete workers. In the case of wood molds, a form is required on the inside surface of the concrete and also on the outside surface. As a result, concrete required a full, double-wall timber construction prior to pouring the concrete. The effort required to construct such a double wall is less than but similar to that required to entirely fabricate a wood two-by structure. Once the static forms are assembled or built, then the concrete must be poured, and, finally, the molds torn down and removed. Furthermore, and unlike with a foundation, seams need to be sealed or protected in some way to prevent the finished concrete from also showing the seam. So, in the prior art timber-based molds, concrete effectively required as much or even more labor and lumber as that required to assemble a lumber house, and then further required the expenses associated with the concrete and pouring. In short, concrete has been a significantly more expensive building material than lumber.
Metal forms manufactured from aluminum and steel have also been devised for casting concrete walls at a job site. Unfortunately, these molds tend to be very expensive, and frequently, due to their size and weight, require special cranes or cable-type lifts to raise and lower the forms. Once a form is placed, various fasteners must be anchored to the surrounding mold forms. When the concrete casting is complete, fasteners must be removed and molds again raised and lowered by cranes and removed from the job site to storage. Once again, the labor associated with this construction, not to mention the additional machinery, exceeds that which would be required for the standard timber construction, therefore driving the cost of the building up once again and reducing the demand for such alternative materials. Furthermore, these massive forms undesirably require substantial storage space when not in use.
Appearance is also an issue with concrete. The casting of concrete can be fairly difficult, and the possibility of a less-than-perfect finished exterior is great. As aforementioned, seams must not be allowed to show, which requires eliminating or hiding the seams in the molds. Furthermore, in the event of an error or flaw, patching or repairing concrete is quite difficult and undesirable. Finally, concrete is not conducive to the placement of utilities such as electrical wiring or plumbing using standard techniques.
Thermal characteristics of concrete, which can be a benefit, also may be a detriment. Exposed concrete surfaces, while acting as a thermal mass, can also be a site for undesirable condensation on a hot and humid day. Concrete does not itself act as a very good thermal insulator, and so may be quite cold on a cold day and get undesirably warm on a hot day.
As a result of the expenses associated with molding and shaping, the difficulties of working with utilities and alterations subsequent to casting, and the issues associated with thermal conductivity and condensation, concrete has traditionally found limited application. Concrete has been reserved for buildings which justify the additional cost as a result of the unique benefits obtained with the material. For example, many schools have been built from concrete, anticipating that the school building will be used for many years to come and desiring that the building provide a safe and durable structure that may also serve the additional purposes of storm shelter, community building, etc. Commercial properties are often manufactured from concrete, for reasons mimicking those for schools. Nevertheless, the methods available for molding the concrete were simply not cost effective for most residential or single-story construction projects.
More recently, a new type of foamed resin form has been devised for molding concrete. This type of form is illustrated, for example, in U.S. Pat. No. 5,896,714 to Cymbala et al; U.S. Pat. No. 5,852,907 to Tobin et al; U.S. Pat. No. 5,845,449 to Vaughan et al; U.S. Pat. No. 5,809,728 to Tremelling; U.S. Pat. No. 5,809,727 to Mensen; U.S. Pat. Nos. 5,809726 and 5,611,182 to Spude; and U.S. Pat. No. 5,803,669 to Bullard; each which is incorporated herein by reference for their relevant teachings. These forms include various features which facilitate assembly of a complete building structure. They may be interlocking, so that the forms are readily stacked, and may also include structure within the form to support various additional components such as re-bar which will serve to reinforce the concrete. Advantageously, these foamed resin forms are designed to remain with the building structure, and so do not require removal after the concrete has been cast. Consequently, the foamed resin form will act as substantial thermal insulation, and a building so constructed will normally not require any further insulation. The resulting walls are thermally insulated against heat and cold, and yet still maintain the benefits of concrete in terms of structural integrity and thermal mass. The resulting structures may be built for much lower cost than when using the traditional timber form and concrete method, and yet provide for an outstanding composite finished product with features and benefits exceeding those of concrete alone.
Nevertheless, and while there are many companies now manufacturing these foam concrete forms in various dimensions and styles, there still remains an issue which has not been adequately resolved. In these prior art construction techniques, footings are most typically framed and poured, and then allowed to cure. Then the foamed resin forms are assembled about these footings or on top of the footings, and then the walls are poured next. Finally, roofing components are installed to complete the exterior structure. Floors may be poured simultaneous with the footings, walls or at any other time as deemed appropriate by the builder. As is apparent, the assembly of footing forms, pouring of concrete and then removal of the footing forms has much of the drawback associated with the older construction techniques found with the walls. Moreover, concrete must be delivered to a job site on two separate occasions, which is also undesirable. Furthermore, the walls and footings are then formed with a seam therebetween, which is also undesirable.
In order to improve the efficiency of construction of a concrete wall and footing, a number of artisans in the construction industry have proposed various forms for simultaneously pouring footings and walls. The following U.S. patents are incorporated herein by reference for their respective teachings of various monolithic forms and construction methods: Kay in U.S. Pat. No. 940,463; May in U.S. Pat. No. 1,563,581; Gremel in U.S. Pat. No. 1,607,072; Jorsch in U.S. Pat. No. 2,250,064; Arrighini in U.S. Pat. No. 2,251,775 and U.S. Pat. No. 2,511,829; Findley in U.S. Pat. No. 2,661,517; Shook in U.S. Pat. No. 2,614,311; Luyben in U.S. Pat. No. 3,722,849; Vetter in U.S. Pat. No. 5,076,535; Schultz in U.S. Pat. No. 5,511,761 and U.S. Pat. No. 5,799,399; Farrington in U.S. Pat. No. 5,882,540; and Zuhl in U.S. Pat. No. 5,922,236. Nevertheless, none of these monolithic forms teach or suggest a way to take advantage of the various foamed resin forms available, and so suffer from the drawbacks noted hereinabove with regard to concrete structures manufactured without foamed resin forms.